Vehicle air suspension having a lifting system

Abstract

There is disclosed a vehicle air suspension of the trailing arm type in which a system for lifting one or more road wheels whose load-bearing capacity is not required comprises a cradle having a platform member on which is supported an air bag. The air bag is disposed, on inflation, to act on a longitudinal member of the suspension so as to urge that member, and a road wheel attached thereto, upwardly. The cradle has a pair of arms which pass to opposite sides of the longitudinal member. Embodiments are disclosed in which the arms are adapted to be secured to a suspension damper mounting, to a pivot of the longitudinal member, or to a suspension bracket of the vehicle.

I claim: 
     
       1. An air suspension system for a vehicle comprising a longitudinal member extending generally lengthways of the vehicle and mounted to the vehicle for pivotal movement about an axis generally transverse of the vehicle, an air spring disposed to act between the longitudinal member rearwards of the axis and the vehicle, and a road wheel carrier disposed on the longitudinal member rearwards of the axis, wherein the suspension system further comprises a lifting system for lifting at least one wheel of the vehicle comprising a cradle having a platform member and two arms each arm connecting the platform member to the vehicle, the arms being disposed to opposite sides of the longitudinal member, the lifting system further comprising an air bag disposed to act between the platform member and the longitudinal member such that inflation of the air bag causes upward pivoting movement of the longitudinal member, so raising the or each wheel connected thereto. 
     
     
       2. An air suspension system according to claim 1 in which the road wheel carrier comprises a stub axle on which one or more wheels is carried, a similar suspension system being provided for opposite wheels on left and right sides of the vehicle. 
     
     
       3. An air suspension system according to claim 1 in which the road wheel carrier comprises an axle extending transversely of the vehicle, to carry road wheels for left and right sides of the vehicle. 
     
     
       4. An air suspension system according to claim 1 further comprising anchorage means by which a lower part of the air bag is secured to the platform member. 
     
     
       5. An air suspension system according to claim 1 further comprising coupling means by which an upper part of the air bag is connected to the longitudinal member. 
     
     
       6. An air suspension system according to claim 5 in which the coupling means substantially prevents relative movement between an upper surface of the air bag, and the longitudinal member. 
     
     
       7. An air suspension system according to claim 1 further comprising guide means interconnecting an upper part of the air bag and the cradle and operable to constrain movement of an upper portion of the air bag relative to the cradle to a desired path. 
     
     
       8. An air suspension system according to claim 7 in which the guide means comprises a beam having end portions or end fittings, and the arms of the cradle have guides or slots within which the end portions or end fittings are constrained to travel. 
     
     
       9. An air suspension system according to claim 1 having bearing means disposed to mechanically interconnect the air bag and the longitudinal member on inflation of the air bag. 
     
     
       10. An air suspension system according to claim 9 in which the bearing means comprises a block of rubber or plastics material. 
     
     
       11. An air suspension system according to claim 1 further comprising pivot means by which the longitudinal member is secured to the vehicle, the cradle being adapted for connection to the pivot means. 
     
     
       12. An air suspension system according to claim 11 in which the pivot means comprises a pivot bolt extending along the transverse axis about which the longitudinal member pivots, the arms of the cradle having holes through which the pivot bolt extends. 
     
     
       13. An air suspension system according to claim 11 in which the pivot means comprises a pivot bolt extending along the transverse axis about which the longitudinal member pivots, the arms of the cradle having holes through which the pivot bolt extends, and the cradle carrying stop means to resist its pivoting about the pivot bolt. 
     
     
       14. An air suspension system according to claim 1, further comprising a suspension damper connected to the longitudinal member and, by pivot means, to the vehicle, the cradle being connected to the vehicle by the pivot means. 
     
     
       15. An air suspension system according to claim 14 in which the pivot means comprises a pivot bolt, the arms of the cradle having holes through which the pivot bolt extends. 
     
     
       16. An air suspension system for a vehicle comprising a longitudinal member extending generally lengthways of the vehicle and mounted to the vehicle for pivotal movement about an axis generally transverse of the vehicle, an air spring disposed to act between the longitudinal member rearwards of the axis and the chassis, a road wheel carrier disposed on the longitudinal member rearwards of the axis, and a suspension damper connected to the longitudinal member and, by mounting means, to the vehicle, the suspension system further comprising a lifting system for lifting at least one wheel of the vehicle comprising a cradle adapted for connection to the said mounting means and an air bag supported by the cradle and arranged, on inflation thereof, to urge the longitudinal member upwardly, so raising the wheel carrier. 
     
     
       17. An air suspension system according to claim 16 in which the mounting means comprises a pivot element, the cradle having members through which the pivot element extends.